This invention relates to a one-piece agitator, preferably enameled, for use in closed enameled vessels having manhole openings therein.
There are three general types of enameled vessels. In one type, frequently referred to as a two piece or clamp top vessel, the entire top head of the vessel can be removed. This facilitates installation of internal components such as agitators and baffles. However, this type of construction increases construction costs and magnifies sealing problems, particularly since adjustments of the seals may be necessary because of distortions of the vessel flanges during enameling of the vessel.
Another type of vessel, sometimes referred to as a one piece vessel with an assembly opening, uses a top head formed integrally with the body of the vessel, but with a relatively large opening in the head through which agitators and the like can be installed. Thus, relatively large container openings are still necessary, with the attendant production costs and sealing problems.
The third type of vessel, frequently referred to as a one piece or closed vessel, features an integral top head with relatively small openings such as pipe connections, openings for agitator and/or baffle shafts, and manhole openings. The largest opening in a vessel of this type is usually the manhole, which is typically much too small to admit a conventional one piece agitator of the size that would be desirable for many applications. Thus, although this type of reactor minimizes the construction costs and sealing problems presented by the clamp top vessel and the one piece vessel with the large assembly opening, it limits the type of agitator that can be installed in the vessel.
Separable enameled agitators--with individual elements that can be introduced through a relatively small opening such as a manhole and assembled inside the vessel--avoid the foregoing problems. Unfortunately, since the seals on these separable agitators are relatively inaccessible and difficult to examine, and since these agitators are frequently exposed to highly corrosive conditions, it is difficult and expensive to provide reliable seals for these separable enameled agitators. Moreover, even in the case of very expensive sealing constructions, the connection points on the agitators form weak points where breakdowns can occur.